The present invention relates to spark-ignition internal combustion engines such as engines that typically power vehicles and other machinery using gasoline or similar fuel.
Spark-ignition internal combustion engines have moderate compression ratios, combustion being initiated by electric arcing rather than by charge heating as in Diesel engines. Spark-ignition engines are less expensive to produce and provide higher specific power output than Diesel engines, being also quieter and smoother running. However, a major shortcoming of conventional spark-ignition engines is the need for spark plugs, which are expensive to produce and often break down, requiring replacement. Aside from this obvious disadvantage, there are other disadvantages with spark-ignition engines. For example:
1. The combustion chamber is difficult to cool because of the close proximity of one or more spark plugs with intake and exhaust ports and associated valve train components; PA1 2. Breathing efficiency is limited by valve area, which is in turn limited by the space taken up by the spark plugs; PA1 3. Other openings in the combustion chamber, such as for injector nozzles and the like, are difficult to provide because of the competing need for spark plug openings; PA1 4. Combustion is inefficient and accompanied by the production of unwanted atmospheric pollutants because ignition originates only from the locations of one or at most a pair of spark plugs per cylinder; and PA1 5. The engines are expensive to produce because of the complicated tooling required to form the combustion chamber with adequate provisions for cooling in the presence of valving and spark plugs that are in close proximity.
Others have attempted to avoid some of these difficulties by locating spark electrodes about the circumference of each cylinder, using conductors imbedded within a head gasket or in specially provided cylinder rings. See, for example, Smits U.S. Pat. Nos. 2,775,234 and 2,948,824, Morrison U.S. Pat. Nos. 2,904,610, and Lowther U.S. Pat. No. 4,330,732. Unfortunately, none of these methods are believed to be commercially successful in that they require unconventional engine layout, excessive head gasket thickness, etc., and/or they are excessively expensive to produce, unreliable and short-lived.
Thus there is a need for a spark-ignition engine that does not require conventional spark plugs, that is inexpensive to produce, relatively free from the production of atmospheric pollutants, reliable, durable and easy to maintain.